Role of Fiber Addition in GFRP-Reinforced Slender RC Columns under Eccentric Compression: An Experimental and Analytical Study

Steel reinforcement is widely used in reinforced concrete (RC) constructions. However, the durability of the steel RC elements is often compromised due to corrosion under adverse environmental conditions. Glass fiber‒reinforced polymer (GFRP) bars have become an attractive alternative for replacing steel bars in several RC applications due to their excellent durability properties. However, the GFRP RC columns exhibit lesser stiffness and fail in a brittle manner compared to steel RC columns. Also, the second-order moments and deformations can increase in the GFRP RC columns due to the low elastic modulus of GFRP bars. The pseudoductility and postcracking behavior of GFRP RC columns can be improved by adding discrete fibers. In this study, 12 steel and GFRP RC slender columns are tested under eccentric compression (e/h ratio of 0.5), and the results are presented. The test matrix consists of (1) steel RC columns without fibers; (2) GFRP RC columns without fibers; and (3) GFRP RC columns with four different fiber dosages of (1) 0.50% and 1.0% of macrosynthetic polyolefin (PO); and (2) 0.5% and 1.0% of hybrid (HB) combination of PO and steel fibers. The test results are compared with analytical predictions considering the geometrical and material nonlinearities. The test results show that adding HB fibers resulted in higher strength and pseudoductile failure than columns reinforced with only PO fibers. HB fibers significantly increased flexural rigidity and the ultimate strength of slender GFRP RC columns.